Television signal scrambling method and apparatus
First Claim
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1. A scrambling apparatus of a television signal including a video signal and an audio signal, comprising:
- analog-to-digital conversion means for converting a first video signal to a digital signal;
memory means for storing the digital signal;
timing generating means for providing a write clock and a read clock to the memory means to write the digital signal to and read the digital signal from the memory means, the provision of the read clock or write clock being temporarily suspended so that a corresponding part of the read-out digital signal is elongated or shortened, respectively, to change the length of a line of the video signal;
digital-to-analog conversion means for converting the digital signal output from the memory means to a second video signal; and
scrambling means for compressing a horizontal sync signal portion and/or a vertical blanking interval portion of the second video signal by a predetermined amount.
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Abstract
A video signal from a video-audio source is converted to a digital signal, and stored in a memory. A read clock or a write clock for the memory is temporarily suspended to elongate or shorten a corresponding part of the digital signal. The elongated/shortened digital signal is converted to an analog video signal; and finally sync/blanking signal portions are compressed by a predetermined amount. The elongating operation may be continued and a one horizontal period part of the digital signal may be deleted when an accumulated elongation time has reached or exceeded one horizontal period.
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Citations
17 Claims
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1. A scrambling apparatus of a television signal including a video signal and an audio signal, comprising:
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analog-to-digital conversion means for converting a first video signal to a digital signal; memory means for storing the digital signal; timing generating means for providing a write clock and a read clock to the memory means to write the digital signal to and read the digital signal from the memory means, the provision of the read clock or write clock being temporarily suspended so that a corresponding part of the read-out digital signal is elongated or shortened, respectively, to change the length of a line of the video signal; digital-to-analog conversion means for converting the digital signal output from the memory means to a second video signal; and scrambling means for compressing a horizontal sync signal portion and/or a vertical blanking interval portion of the second video signal by a predetermined amount. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for scrambling a television signal including a video signal and an audio signal, comprising the steps of:
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converting a first video signal to a digital signal; elongating/shortening a part of the digital signal to change the length of a line of the video signal; converting the elongated/shortened digital signal to a second video signal; compressing a horizontal sync signal portion and/or a vertical blanking interval portion of the second video signal by a predetermined amount. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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Specification